1. Field of the Invention
The present invention relates to map information providing methods and a terminal device used in the methods, and more particularly to a map information providing method in which a base station provides a plurality of kinds of map information through a broadcast channel to a terminal device which can move freely in the service area and to the terminal device used in the method.
2. Description of the Background Art
Conventionally, for example, Japanese Patent Laying-Open No.8-22246 discloses a map information providing system in which a base station and terminal devices are communicably connected so that the terminal devices can receive and display map information transmitted from the base station. More specifically, the base station transmits predetermined map information to terminal devices. The terminal devices receive and display the map information so that the users can utilize the map information.
In this case, the users do not always utilize all map information transmitted from the base station, so they will want to store only necessary map information in storage devices. However, conventional map information providing systems do not allow the terminal devices to select required information out of the map information transmitted. Therefore they must store the map information including unnecessary information in the storage devices. This requires that the terminal devices be equipped with storage devices having larger capacity than required.
Further, the map information is frequently updated because of constructions of new roads and buildings, for example. However, the conventional terminal devices are incapable of managing versions of the map information, and they repeatedly receive map information of the same version and store the information in storage devices, which also leads to an increase in capacity of the storage devices.